Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 745 · 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 iron setting (b) the same paper (c) how dark the writing is (d) the ironing time
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
3. 3.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
5. 5.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a magnet (d) a mirror
7. 7.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
8. 8.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
9. 9.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) white paper (d) a battery cell
11. 11.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
12. 12.True or false: putting the iron away is a job a child can do. (a) False (b) True
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the ironing time (c) the same paper (d) the kind of juice
14. 14.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
15. 15.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
16. 16.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
17. 17.⚖️ 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
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) a cotton bud (d) an adult with an iron
19. 19.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a battery cell (d) a magnet
20. 20.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) letting the paper dry
21. 21.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
22. 22.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
23. 23.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
24. 24.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
25. 25.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
26. 26.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
27. 27.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
28. 28.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
30. 30.⚖️ 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
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) lemon juice (d) a small bowl
32. 32.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
33. 33.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) reading the message
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
35. 35.True or false: ironing the paper is a job a child can do. (a) False (b) True
36. 36.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
37. 37.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
38. 38.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
39. 39.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) letting the paper dry
40. 40.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) cutting the lemon

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