Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 103 · 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 what we measure? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is (d) the ironing time
2. 2.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
3. 3.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
4. 4.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
5. 5.⚖️ 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
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
7. 7.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
8. 8.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
9. 9.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same paper (c) the kind of juice
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
12. 12.🍋 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) reading the message
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
14. 14.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
17. 17.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
18. 18.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) turmeric powder (d) lemon juice
20. 20.⚖️ 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
21. 21.True or false: plugging in the iron is a job a child can do. (a) False (b) True
22. 22.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) dark brown words (d) blue words
23. 23.🔮 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
24. 24.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
25. 25.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) white paper (c) a cotton bud (d) an adult with an iron
27. 27.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the ironing time (d) the iron setting
29. 29.⚖️ 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) True (b) False
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) white paper (d) a cotton bud
31. 31.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
32. 32.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
33. 33.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) reading the message
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) lemon juice (d) an adult with an iron
35. 35.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) plugging in the iron
36. 36.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) ironing the paper
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a small bowl (c) an adult with an iron (d) a cotton bud
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a magnet (c) turmeric powder (d) yeast
39. 39.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
40. 40.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True

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