Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 247 · 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.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
4. 4.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
5. 5.⚖️ 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
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
7. 7.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
8. 8.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) lemon juice (d) a small bowl
11. 11.True or false: white paper is not 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) a magnet (b) white paper (c) a small bowl (d) a cotton bud
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) a cotton bud (d) a small bowl
14. 14.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
15. 15.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
17. 17.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) ironing the paper
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) a small bowl (d) white paper
19. 19.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
20. 20.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
21. 21.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) writing the message (d) letting the paper dry
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
23. 23.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
24. 24.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic
26. 26.⚖️ 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
27. 27.True or false: yeast is needed for the secret lemon message. (a) True (b) False
28. 28.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
29. 29.True or false: putting the iron away is a job a child can do. (a) False (b) True
30. 30.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a magnet (d) a small bowl
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) yeast
33. 33.⚖️ 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
34. 34.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
35. 35.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a cotton bud (d) yeast
37. 37.⚖️ 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
38. 38.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the same cotton bud
40. 40.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids