Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 738 · 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) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) reading the message
2. 2.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
3. 3.⚖️ 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 kind of juice (c) how dark the writing is (d) the ironing time
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) turmeric powder (d) a magnet
5. 5.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) putting the iron away (d) plugging in the iron
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a small bowl (d) an adult with an iron
7. 7.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
9. 9.True or false: ironing the paper is a job for an adult. (a) True (b) False
10. 10.True or false: ironing the paper is a job a child can do. (a) True (b) False
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
12. 12.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) yeast (d) an adult with an iron
14. 14.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
16. 16.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
17. 17.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
18. 18.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) letting the paper dry (d) ironing the paper
19. 19.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) plugging in the iron
20. 20.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) cutting the lemon
21. 21.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
22. 22.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
23. 23.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a battery cell
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same paper
26. 26.⚖️ 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
27. 27.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) ironing the paper
28. 28.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) lemon juice (d) a small bowl
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a battery cell (d) lemon juice
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud
33. 33.True or false: reading the message is a job for an adult. (a) False (b) True
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
35. 35.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
36. 36.True or false: writing the message is a job for an adult. (a) True (b) False
37. 37.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) physical (d) musical
38. 38.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
39. 39.⚖️ 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 change it (c) we keep it the same
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False

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