Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 303 · 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 is needed for the secret lemon message? (a) yeast (b) a magnet (c) a small bowl (d) turmeric powder
2. 2.True or false: cutting the lemon is a job a child can do. (a) False (b) True
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a balloon (d) a cotton bud
4. 4.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
5. 5.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) a small bowl (d) lemon juice
6. 6.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) writing the message
7. 7.True or false: cutting the lemon is a job for an adult. (a) True (b) False
8. 8.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
9. 9.⚖️ 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
10. 10.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a cotton bud (c) a balloon (d) a magnet
11. 11.True or false: white paper is needed for the secret lemon message. (a) False (b) True
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) turmeric powder (d) a cotton bud
13. 13.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same paper (c) the ironing time (d) how dark the writing is
15. 15.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) writing the message (d) ironing the paper
16. 16.True or false: letting the paper dry is a job a child can do. (a) False (b) True
17. 17.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud (d) the ironing time
20. 20.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
21. 21.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) chemical (c) physical (d) magnetic
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
23. 23.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
24. 24.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) a rainbow (c) blue words (d) dark brown words
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a small bowl (c) a cotton bud (d) an adult with an iron
26. 26.True or false: yeast is needed for the secret lemon message. (a) False (b) True
27. 27.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) yeast (d) a small bowl
30. 30.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
31. 31.⚖️ 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) True (b) False
32. 32.⚖️ 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 change it (c) we measure it
33. 33.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) writing the message (d) reading the message
34. 34.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
35. 35.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) white paper (d) a mirror
36. 36.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) lemon juice (d) a battery cell
37. 37.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
38. 38.True or false: putting the iron away is a job a child can do. (a) True (b) False
39. 39.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
40. 40.True or false: putting the iron away is a job for an adult. (a) False (b) True

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