Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 155 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
2. 2.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a magnet (d) lemon juice
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 kind of juice (b) the same paper (c) how dark the writing is (d) the same cotton bud
5. 5.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a small bowl (d) a battery cell
6. 6.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the kind of juice (c) the same paper (d) how dark the writing is
8. 8.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) ironing the paper (c) reading the message (d) writing the message
9. 9.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) plugging in the iron
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) lemon juice (d) a cotton bud
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
15. 15.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a cotton bud (d) yeast
17. 17.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) writing the message
18. 18.True or false: writing the message is a job for an adult. (a) True (b) False
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) turmeric powder
20. 20.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) reading the message
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
22. 22.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) plugging in the iron
23. 23.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
24. 24.True or false: cutting the lemon is a job a child can do. (a) True (b) False
25. 25.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
26. 26.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) a balloon (d) a magnet
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
28. 28.⚖️ 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
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) a small bowl (d) a cotton bud
30. 30.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
31. 31.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) letting the paper dry (d) ironing the paper
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) white paper (d) a magnet
33. 33.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
34. 34.⚖️ 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 kind of juice (c) the same cotton bud
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
36. 36.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
38. 38.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
39. 39.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
40. 40.True or false: letting the paper dry is a job a child can do. (a) True (b) False

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