Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 658 · 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.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) yeast (d) a small bowl
5. 5.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
6. 6.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) reading the message
7. 7.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) writing the message (d) cutting the lemon
8. 8.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
10. 10.True or false: letting the paper dry is a job a child can do. (a) True (b) False
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) lemon juice (d) a cotton bud
12. 12.True or false: plugging in the iron is a job a child can do. (a) True (b) False
13. 13.True or false: reading the message is a job for an adult. (a) False (b) True
14. 14.True or false: cutting the lemon is a job a child can do. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
16. 16.⚖️ 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
17. 17.True or false: ironing the paper is a job for an adult. (a) False (b) True
18. 18.⚖️ 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) False (b) True
19. 19.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) putting the iron away (d) cutting the lemon
20. 20.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
21. 21.⚖️ 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
22. 22.True or false: putting the iron away is a job for an adult. (a) True (b) False
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a balloon (d) white paper
24. 24.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
25. 25.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a small bowl (c) a cotton bud (d) an adult with an iron
27. 27.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
28. 28.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
29. 29.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
31. 31.🍋 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
32. 32.🛟 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
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) yeast (d) turmeric powder
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
35. 35.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) writing the message
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
37. 37.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) letting the paper dry (d) ironing the paper
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) lemon juice (d) turmeric powder
39. 39.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
40. 40.True or false: writing the message is a job a child can do. (a) False (b) True

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