Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 229 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) turmeric powder
3. 3.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the ironing time (c) how dark the writing is (d) the kind of juice
5. 5.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a balloon (c) lemon juice (d) white paper
9. 9.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) magnetic (d) physical
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
11. 11.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
12. 12.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a battery cell (d) an adult with an iron
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) yeast
15. 15.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
16. 16.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
17. 17.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
18. 18.True or false: white paper is needed for the secret lemon message. (a) True (b) False
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
20. 20.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it can burn skin (d) it is sticky
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
23. 23.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) reading the message
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the iron setting (c) how dark the writing is
25. 25.True or false: ironing the paper is a job for an adult. (a) False (b) True
26. 26.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
28. 28.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
30. 30.True or false: cutting the lemon is a job a child can do. (a) True (b) False
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
32. 32.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a cotton bud (c) an adult with an iron (d) lemon juice
34. 34.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) putting the iron away (d) letting the paper dry
35. 35.🍋 Which of these steps is a job for an adult? (a) writing the message (b) putting the iron away (c) reading the message (d) dipping the cotton bud
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
38. 38.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
39. 39.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
40. 40.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing

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