Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 110 · 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.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
3. 3.True or false: putting the iron away is a job a child can do. (a) False (b) True
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
5. 5.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
6. 6.⚖️ 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
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a mirror (d) a small bowl
8. 8.True or false: letting the paper dry is a job for an adult. (a) True (b) False
9. 9.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a battery cell (d) white paper
11. 11.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
12. 12.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
13. 13.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) yeast (d) a battery cell
14. 14.True or false: reading the message is a job for an adult. (a) False (b) True
15. 15.True or false: white paper is needed for the secret lemon message. (a) False (b) True
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same paper (c) the same cotton bud (d) how dark the writing is
17. 17.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
18. 18.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) reading the message
19. 19.True or false: cutting the lemon is a job for an adult. (a) False (b) True
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) white paper (d) lemon juice
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 ironing time (c) the kind of juice
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a balloon (d) lemon juice
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
24. 24.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
25. 25.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a mirror
27. 27.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
28. 28.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
29. 29.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
30. 30.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) it turned into air (d) the ink is magnetic
31. 31.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
32. 32.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
33. 33.🛟 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
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the same cotton bud (c) how dark the writing is (d) the kind of juice
35. 35.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
36. 36.True or false: ironing the paper is a job a child can do. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky

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