Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 345 · 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.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
2. 2.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) putting the iron away (d) plugging in the iron
3. 3.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) cutting the lemon
4. 4.⚖️ 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
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) writing the message
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) a magnet
7. 7.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
8. 8.True or false: ironing the paper is a job a child can do. (a) False (b) True
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
11. 11.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) putting the iron away
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) a mirror
13. 13.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
14. 14.True or false: cutting the lemon is a job a child can do. (a) True (b) False
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) white paper (d) lemon juice
16. 16.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the iron setting (c) how dark the writing is (d) the same cotton bud
19. 19.⚖️ 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 iron setting (c) the kind of juice (d) the same cotton bud
20. 20.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
23. 23.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) dipping the cotton bud (d) reading the message
24. 24.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
25. 25.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
26. 26.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
27. 27.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) writing the message
28. 28.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) ironing the paper (d) dipping the cotton bud
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) yeast (c) a cotton bud (d) an adult with an iron
30. 30.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) a balloon
32. 32.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
33. 33.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) a battery cell (d) lemon juice
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a mirror (d) a cotton bud
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) white paper (d) an adult with an iron
39. 39.True or false: ironing the paper is a job for an adult. (a) True (b) False
40. 40.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words

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