Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 790 · 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.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
2. 2.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
5. 5.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) writing the message
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) an adult with an iron (d) a small bowl
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) an adult with an iron (d) yeast
9. 9.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) letting the paper dry
10. 10.🍋 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) ironing the paper
11. 11.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
12. 12.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
13. 13.True or false: cutting the lemon is a job a child can do. (a) False (b) True
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) an adult with an iron (d) a mirror
15. 15.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a battery cell (d) a small bowl
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a cotton bud (d) turmeric powder
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.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
21. 21.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
22. 22.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
23. 23.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
24. 24.⚖️ 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) how dark the writing is (c) the kind of juice (d) the iron setting
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) white paper
26. 26.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) reading the message
27. 27.True or false: putting the iron away is a job for an adult. (a) True (b) False
28. 28.True or false: writing the message is a job for an adult. (a) False (b) True
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
31. 31.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
33. 33.True or false: white paper is needed for the secret lemon message. (a) False (b) True
34. 34.True or false: putting the iron away is a job a child can do. (a) False (b) True
35. 35.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
36. 36.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
37. 37.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
38. 38.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
39. 39.True or false: reading the message is a job for an adult. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same

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